Variable power adjustment access method in CDMA mobile communication system

ABSTRACT

An access method for the variable power adjustment in the code division multiple access mobile communication system is disclosed in the invention, the prefix of the physical random access channel, and the access, conflict detection prefix of the physical common packet channel are received and performed the quality evaluation by the base station, respectively; the precise control of the transmission power of the subsequent message section of the physical random access channel, conflict detection prefix of the physical common packet channel, and the power control prefix, the message section are obtained based on the quality evaluation value; the control indication of the precise control is transmitted via the down link acquisition indication channel, access prefix acquisition indication channel, and conflict detection/channel assignment indication channel; and the subsequent message section of the physical random access channel and the conflict detection of the physical common packet channel and the power control prefix, message section are transmitted by the user equipment by using a value among the power bias values. The said method can use the accuracy of the power control of the physical random access channel and the physical common packet channel, which can be transmitted on the up link, to reduce the interference to the other channels and to increase the capacity of the system.

FIELD OF THE INVENTION

[0001] The invention relates to the access of the mobile communicationsystem, particularly, relates to an access method for the variable poweradjustment. The said method supports the physical random access channel(PRACH) and the physical common packet channel (PCPCH) of the up link,the acquisition indication channel (AICH), the access prefix acquisitionindication channel (AP-ACH), and the conflict detection/channelassignment indication channel (CD/CA-ICH) of the down link by moreprecise power control.

BACKGROUND OF THE INVENTION

[0002] In the access technology of the radio communication, there is anaccess method based on the fast indication. The burst data of the accesscan often be divided into several sections, the next section of theinformation is transmitted normally only when the responses of the datain the preceding sections (For example, an acquisition response, and thelike) have been received. Normally, this type of responses only hasresponses with two values of 1 and −1, or with three values of 1, −1,and 0. Wherein, only one value, for example 1, is used for theindication acquired successfully and allowed to access. Thus, the moreprecise control function can not be sufficient.

[0003] Please refer to FIG. 1 and FIG. 2, in the access of the physicalrandom access channel (PRACH) and the physical common packet channel(PCPCH) of the up channels in WCDAM, the fast indication method is usedfor indicating the prefix acquisition situation. For the physical randomaccess channel (PRACH), the acquisition indication channel (AICH) isused to indicate the acquisition on the down link. For PCHCH, the accessprefix acquisition indication channel (AP-ACH) and the conflictdetection/channel assignment indication channel (CD/CA-ICH) are used.For the physical random access channel (PRACH), a value evaluated by theopen loop power is firstly used by the user equipment as thetransmission prefix of the initial transmission power. If theacquisition indication information of the down link acquisitionindication channel (AICH) has not been received (or the receivedacquisition indication information is 0), then another prefix willcontinuously be transmitted subsequently by adding power ΔP0. If thereceived acquisition indication is −1, then it will exit the procedureand report to the upper layer. If the received acquisition indication is1, then the information section will be transmitted by using a preamblepower bias ΔPp−m corresponding to the last successful access.

[0004] In this way, because an error may be reach +/−12 dB under anextreme situation of the open loop power evaluation, and considering thethroughput of the physical random access channel (PRACH), ΔP0 being nottaken very small, and the affect of the channel fading, AP power whichis accessed successfully at last and the acquisition probability at thesaid power may change significantly. If this is taken as a referencepower to transmit the signals of the information section by increasingthe power bias ΔPp−m (once this parameter is assigned by the high layer,all of the user equipment will use this fix parameter in a long periodunless reassigning), the variation range of the power of the informationsection may also be very large, causing the comprehensive performance ofaccessing the entire physical random access channel (PRACH) worse.

[0005] The access procedure for the physical common packet channel(PCPCH) is slightly similar as that of the physical random accesschannel (PRACH), a transmitted access prefix AP is evaluated firstly bythe user equipment based on the open loop power. If the acquisitionindication information of the down link prefix acquisition indicationchannel (AP-AICH) is not received (or the acquisition indication is 0),then the prefix will continuously be transmitted by using power biasΔP0. If the received acquisition indication is 1, then the conflictdetection prefix (CD-P) will be transmitted by using the same power.

[0006] If the corresponding conflict detection prefix (CD-P) is notreceived in the conflict detection/channel assignment indication channel(CD/CA-ICH), then the procedure will be exited and reported to the upperlayer. If it is received, then the power control prefix and the messagesection are transmitted by using the power bias of ΔPp−m.

[0007] For the same reason as that for accessing the physical randomaccess channel (PRACH), AP power which is accessed successfully at lastof the physical common packet channel (PCPCH) and the acquisitionprobability based on the said power may change significantly. In thisway, the conflict detection transmitted subsequently and the powercontrol prefix and the initial power of the message section will alsochange significantly. Thus, it causes the comprehensive performance ofthe entire link worse.

[0008] The frame format of the acquisition indication channel (AICH) inWCDMA is shown in FIG. 3, wherein,$a_{j} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{s}b_{s,j}}}$

[0009] The value of acquisition indication AI is taken as 1, 0, and −1based on the result of the acquisition. S represents the sequence numberof the characteristic code. See Table 1 for the value of bs and j (Table1 is a characteristic code table of the acquisition indication channel):TABLE 1 s b_(s,0), b_(s,1) . . . , b_(s,31) 0 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 2 1 1 1 1 −1 −1−1 −1 1 1 1 1 −1 −1 −1 −1 1 1 3 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 1 11 1 4 1 1 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 1 1 5 1 1 −1 −1 1 1 −1 −1−1 −1 1 1 −1 −1 1 1 1 1 6 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 1 1 1 1 1 1 71 1 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 1 1 8 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 −1 −1 9 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 −1 −1 10 1 1 1 1−1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 −1 −1 11 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1−1 −1 1 1 −1 −1 12 1 1 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 −1 −1 13 1 1−1 −1 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 −1 −1 14 1 1 1 1 −1 −1 −1 −1 −1 −1−1 −1 1 1 1 1 −1 −1 15 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 −1 −1 sb_(s,0), b_(s,1) . . . , b_(s,31) 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 −1 −11 1 −1 −1 1 1 −1 −1 1 1 −1 −1 2 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 −1 −1 3 −1−1 −1 −1 1 1 1 1 −1 −1 −1 −1 1 1 4 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 5−1 −1 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 6 1 1 −1 −1 −1 −1 −1 −1 −1 −1 1 1 11 7 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 8 −1 −1 −1 −1 −1 −1 −1 −1 −1 −1−1 −1 −1 −1 9 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 10 −1 −1 1 1 1 1 −1 −1−1 −1 1 1 1 1 11 1 1 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1 12 −1 −1 −1 −1 −1 −11 1 1 1 1 1 1 1 13 1 1 −1 −1 1 1 1 1 −1 −1 1 1 −1 −1 14 −1 −1 1 1 1 1 11 1 1 −1 −1 −1 −1 15 1 1 1 1 −1 −1 1 1 −1 −1 −1 −1 1 1

[0010] Thus, it is stipulated in the current protocol that theacquisition indication channel can only have three types of indicationsof 0, 1, and −1 for a certain characteristic code. Wherein, only theacquisition indication “1” is used to indicated that the accessing isallowed, however, more precise power control information cannot beprovided.

[0011] The same format as that used for the acquisition indicationchannel (AICH) can be used to transmit the prefix acquisition indicationchannel (AP-ACH).

[0012] For the conflict detection/channel assignment indication channel(CD/CA-ICH),$a_{j} = {{\sum\limits_{i = 0}^{15}\quad {{CDI}_{i} \times b_{{si},j}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k} \times b_{{sk},j}}}}$

[0013] wherein, CDIi and CAIk generate the value, refer to Table 2(Table 2 is a generation table for CDIi and CAIi in the conflictdetection/channel assignment indication channel); TABLE 2 Conflictdetection prefix i Channel transmitted characteristic assignmentCharacteristic by user code sequence code equipment i CDI_(i) s_(i)number k CAI_(k) s_(k) 0 +1/0 1 0 +1/0 0 1 −1/0 1 −1/0 2 +1/0 3 2 +1/0 83 −1/0 3 −1/0 4 +1/0 5 4 +1/0 4 5 −1/0 5 −1/0 6 +1/0 7 6 +1/0 12 7 −1/07 −1/0 8 +1/0 9 8 +1/0 2 9 −1/0 9 −1/0 10 +1/0 11 10 +1/0 10 11 −1/0 11−1/0 12 +1/0 13 12 +1/0 6 13 −1/0 13 −1/0 14 +1/0 15 14 +1/0 14 15 −1/015 −1/0

[0014] Therefore, only two indications of 1 and −1 are used to indicatethat the conflict detection has been acquired, and it is unable toprovide to the user equipment the more precise control indication.

[0015] Because the power fluctuation range of the current physicalrandom access channel (PRACH) and physical common packet channel (PCPCH)is very large when acquiring, however, only one indication is used forpermitting access when the acquisition is successful, thus, it causesthe fluctuation range of the subsequent information transmission power,which takes the said power as a power bias reference, of the subsequentsections also being very large, and causing the whole access performancedegrading.

SUMMARY OF THE INVENTION

[0016] The object of the invention is to aim at the above disadvantagesexisting in the access transmission of code division multiple access andto provide an access method having variable power adjustment to increasethe comprehensive performance of the entire system.

[0017] In order to realize the above object, the following technicalscheme is employed in the invention:

[0018] An access method for the variable power adjustment in the codedivision multiple access mobile communication system of the invention,the said method is based on the base station and the user equipment, theacquisition information is obtained by the base station throughreceiving on the up link the prefix of the physical random accesschannel, the access prefix of the physical common packet channel and theconflict detection prefix and evaluating the quality, respectively; theprecise control of the transmission power of the subsequent messagesection of the physical random access channel, conflict detection prefixof the physical common packet channel, and the power control prefix, themessage section are obtained based on the quality evaluation value; thecontrol indication of the said precise control is transmitted via thedown link acquisition indication channel, access prefix acquisitionindication channel, and conflict detection/channel assignment indicationchannel; and after receiving the said power control indication by theuser equipment, the subsequent message section of the physical randomaccess channel, conflict detection prefix of the physical common packetchannel, and the power control prefix, the message section aretransmitted by using a value among a plurality of power bias values.

[0019] Because after the above method being employed by the invention,the entire system can satisfy different functions, particularly, thefunctions of the transmission power being controlled more precisely, andthe receive performance of the link being improved, it is indicatedspecifically as follows:

[0020] 1. The accuracy of the power control of the up link transmittedphysical random access channel and physical common packet channel, andthe successful probability can be improved.

[0021] 2. The average transmission power of the physical random accesschannel and physical common packet channel for achieving the same accessperformance can be saved, the interference to other channel can bedecreased, and the capacity of the entire system can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is an illustration diagram of an access procedure of thephysical random access channel of WCDMA;

[0023]FIG. 2 is an illustration diagram of an access procedure of thephysical common packet channel of WCDMA; and

[0024]FIG. 3 is an illustration of a frame format for acquiring theindication channel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] By analyzing the deficiencies in the aspect of the accessacquisition indication of the prior schemes, a method of the inventionprovides a scheme, in which, the power transmission can be adjusted moreprecisely on the up link channels of the physical random access channel(PRACH) and the physical common packet channel (PCPCH), and more preciseaccess acquisition indication can be provided on the corresponding downlink acquisition indication channel (AICH), AP-acquisition indicationchannel (AICH), and conflict detection/channel assignment indicationchannel (CD/CA-ICH).

[0026] The method of the invention is based on the base station and theuser equipment, the said method is based on the base station and theuser equipment, the acquisition information is obtained by the basestation through receiving on the up link the prefix of the physicalrandom access channel, the common access prefix of the physical commonpacket channel and the conflict detection prefix and evaluating thequality, respectively; the precise control of the transmission power ofthe subsequent message section of the physical random access channel,conflict detection prefix of the physical common packet channel, and thepower control prefix, the message section are obtained based on thequality evaluation value; the control indication of the said precisecontrol is transmitted via the down link acquisition indication channel,access prefix acquisition indication channel, and conflictdetection/channel assignment indication channel; and after receiving thesaid power control indication by the user equipment, the subsequentmessage section of the physical random access channel, conflictdetection prefix of the physical common packet channel, and the powercontrol prefix, the message section are transmitted by using a valueamong a plurality of power bias values.

[0027] Please refer to FIG. 3, the format of the acquisition indicationchannel and access prefix acquisition indication channel having the saidprecise control indication is:$a_{2k} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{1s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{2s}{P_{s}(k)}}}},{k = 0},{{1{\cdots 15}};}$

[0028] wherein, Ps(k) is a prefix characteristic code, please refer toTable 3 for its value (Table 3 is an acquisition indication channelcharacteristic code table employed in the invention): TABLE 3 prefixcharacteristic value of N code 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15P₀(n) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 P₁(n) 1 −1 1 −1 1 −1 1 −1 1 −1 1−1 1 −1 1 −1 P₂(n) 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 1 −1 −1 P₃(n) 1 −1 −11 1 −1 −1 1 1 −1 −1 1 1 −1 −1 1 P₄(n) 1 1 1 1 −1 −1 −1 −1 1 1 1 1 −1 −1−1 −1 P₅(n) 1 −1 1 −1 −1 1 −1 1 1 −1 1 −1 −1 1 −1 1 P₆(n) 1 1 −1 −1 −1−1 1 1 1 1 −1 −1 −1 −1 1 1 P₇(n) 1 −1 −1 1 −1 1 1 −1 1 −1 −1 1 −1 1 1 −1P₈(n) 1 1 1 1 1 1 1 1 −1 −1 −1 −1 −1 −1 −1 −1 P₉(n) 1 −1 1 −1 1 −1 1 −1−1 1 −1 1 −1 1 −1 1 P₁₀(n) 1 1 −1 −1 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1P₁₁(n) 1 −1 −1 1 1 −1 −1 1 −1 1 1 −1 −1 1 1 −1 P₁₂(n) 1 1 1 1 −1 −1 −1−1 −1 −1 −1 −1 1 1 1 1 P₁₃(n) 1 −1 1 −1 −1 1 −1 1 −1 1 −1 1 1 −1 1 −1P₁₄(n) 1 1 −1 −1 −1 −1 1 1 −1 −1 1 1 1 1 −1 −1 P₁₅(n) 1 −1 −1 1 −1 1 1−1 −1 1 1 −1 1 −1 −1 1

[0029] The values of AI₁ and AI₂ can be taken as 0, 1, and −1, ninecontrol indications can be produced by combining AI₁ and AI₂. The formatof the said conflict detection/channel assignment indication channel is:$a_{2l} = {{\sum\limits_{i = 0}^{15}\quad {{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k,2}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1{\cdots 15}};}$

[0030] wherein,

[0031] CDI₁, CAI₂, can be taken as 0, 1, and −1.

[0032] The definitions of T1, T₀, and T⁻¹ are as follows:

T₁={(1, 1), (1, 0), (0, 1)};

T₀={(0, 0), (1, −1), (−1, 1)};

T⁻¹={(−1, −1), (−1, 0), (0, −1)}.

[0033] In the power adjustment of the messages of the said physicalrandom access channel,

[0034] when the acquisition indications of the received down linkacquisition indication channel are (0, 0), (1, −1), (−1, 1), then theprefixes will be transmitted by using continuously the power bias ΔP0;

[0035] when (0, −1), (−1, 0), (−1, −1) are received, then the accesswill be exited and reported to the upper layer;

[0036] when (1, 1) is received, then the messages will be transmitted byusing the power bias ΔPp−m;

[0037] when (1, 0) is received, then the messages will be transmitted byusing the power bias ΔPp−m+ΔP1;

[0038] when (0, 1) is received, then the messages will be transmitted byusing the power bias (ΔPp−m+2*ΔP1).

[0039] After the down link access prefix acquisition indication channelis received by the said physical common packet channel,

[0040] when the access prefix acquisition indications received by theuser equipment on the down link are (0, 0), (1, −1), (−1, 1), then theaccess prefixes will be transmitted by using continuously the power biasΔP0;

[0041] when (0, −1), (−1, 0), (−1, −1) are received, then the accesswill be exited and reported to the upper layer;

[0042] when (1, 1) is received, then the messages will be transmitted byusing the same power bias;

[0043] when (1, 0) is received, then the messages will be transmitted byusing the power bias ΔP1;

[0044] when (0, 1) is received, then the messages will be transmitted byusing the power bias (2*ΔP1).

[0045] After the indications of the transmission power bias indicated bythe conflict detection/channel assignment indication channel is receivedby the said physical common packet channel, if it is in T₀ set, then theaccess procedure will be exited; if those in T₁ or T⁻¹ set are received,then an acquisition will be indicated, and the power biases of thesubsequent power control prefixes and the messages will be determined bythe specific values of T₁ or T⁻¹; when the received indication is (1, 1)or (−1, −1), then the power control prefixes and messages will betransmitted by using the power bias ΔPp−m; if the received indication is(1, 0) or (−1, 0), then the power control prefixes and messages will betransmitted by using the power bias (ΔPp−m+ΔP1); if the receivedindication is (0, 1) or (0, −1), then the power control prefixes andmessages will be transmitted by using the power bias (ΔPp−m+2*ΔP1).

[0046] Similarly, the frame format in FIG. 3 is employed, however,wherein$a_{2k} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{1,s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{2,s}{P_{s}(k)}}}},{k = 0},{{1{\cdots 15}};}$

[0047] The values of AI1 and AI2 can be taken as 0, 1, and −1. In thisway, The value AI is composed of (AI1, AI2), and total 9 combinationsare possible: (0, 0), (0, 1), (0, −1), (1, 0), (1, 1), (1, −1), (−1, 0),(−1, 1), and (−1, −1). In this way, sufficient acquisition indicationscan be transmitted to use for more precise power control or other usage.

[0048] For AP-acquisition indication channel (AICH), a modificationmethod same as that of the acquisition indication channel (AICH) can beused.

[0049] For the conflict detection/channel assignment indication channel(CD/CA-ICH),$a_{2l} = {{\sum\limits_{i = 0}^{15}\quad {{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k,1}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1{\cdots 15}};}$

[0050] The generation of CDIi (composed of (CDIi, 1, CDIi, 2)) and CAIk(composed of (CAIk, 1, CAIk, 2)) can be defined in the following Table 4(Table 4 is a generation table for CDIi and CAIi in the conflictdetection/channel assignment indication channel employed in theinvention): TABLE 4 Conflict detection prefix i charac- Channeltransmitted teristic assignment Characteristic by user code sequencecode equipment i CDI_(i) s_(i) number k CAI_(k) s_(k) 0 T₁/T₀ 1 0 T₁/T₀0 1 T⁻¹/T₀ 1 T⁻¹/T₀ 2 T₁/T₀ 3 2 T₁/T₀ 8 3 T⁻¹/T₀ 3 T⁻¹/T₀ 4 T₁/T₀ 5 4T₁/T₀ 4 5 T⁻¹/T₀ 5 T⁻¹/T₀ 6 T₁/T₀ 7 6 T₁/T₀ 12 7 T⁻¹/T₀ 7 T⁻¹/T₀ 8 T₁/T₀9 8 T₁/T₀ 2 9 T⁻¹/T₀ 9 T⁻¹/T₀ 10 T₁/T₀ 11 10 T₁/T₀ 10 11 T⁻¹/T₀ 11T⁻¹/T₀ 12 T₁/T₀ 13 12 T₁/T₀ 6 13 T⁻¹/T₀ 13 T⁻¹/T₀ 14 T₁/T₀ 15 14 T₁/T₀14 15 T⁻¹/T₀ 15 T⁻¹/T₀

[0051] Three sets are defined, for example:

T1={(1, 1), (1, 0), (0, 1)};

T0={(0, 0), (1, −1), (−1, 1)};

T−1={(−1, −1), (−1, 0), (0, −1)};

[0052] The conditions of the sets may be those, but it is not limited.

[0053] AI indications with more values can be received by the userequipment in the channel of the up link physical random access channel(PRACH). The power adjustment can be performed more precisely totransmit the subsequent messages based on theses received indications.One adjustment scheme is that after Preamble being transmitted by theuser equipment, if the acquisition indications of the received down linkacquisition indication channel (AICH) are (0, 0), (1, −1), (−1, 1), thenPreamble will be transmitted by using continuously the power bias ΔP0.If (0, −1), (−1, 0), (−1, −1) are received, then the procedure will beexited and the upper layer will be reported to. If (1, 1) is received,then the messages are transmitted by using the power bias ΔPp−m. If (1,0) is received, then the messages will be transmitted by using the powerbias (ΔPp−m+ΔP1). If (0, 1) is received, then the messages will betransmitted by using the power bias (ΔPp−m+2*ΔP1).

[0054] If more acquisition power adjustment indications are to be added,the other received information can be defined as the power adjustmentindications, for example, (1, −1), (−1, 1), and the like.

[0055] Similarly, in the up link physical common packet channel (PCPCH),when the indications (0, 0), (1, −1) , (−1, 1) of AP-AI are received bythe user equipment on the down link, then AP will be transmitted byusing continuously the power bias ΔP0. If (0, −1), (−1, 0), (−1, −1) arereceived, then the procedure will be exited and the upper layer will bereported to. If (1, 1) is received, then CD-P will be transmitted byusing the same power bias. If (1, 0) is received, then the CD-P will betransmitted by using the power bias ΔP1. If (0, 1) is received, thenCD-P will be transmitted by using the power bias 2*ΔP1.

[0056] If after CD being transmitted by the user equipment and theacquisition indication for CD-P being received in the down link conflictdetection/channel assignment indication channel (CD/CA-ICH), if it is inT0 set, then the procedure will be exited. If T1 set or T−1 set (basedon the SIGNATURE number for transmitting CD-P, and the same hereinafter)is received, then an acquisition will be indicated. The subsequent powerbias of PCP and the messages will be determined based on the specificvalues of T1 or T−1: when the received indication is (1, 1) or (−1, −1),then PCP and the messages will be transmitted by using the power biasΔPp−m. If the received indication is (1, 0) or (−1, 0), then the PCP andthe messages will be transmitted by using the power bias (ΔPp−m+ΔP1). Ifthe received indication is (0, 1), or (0, −1), then PCP and the messageswill be transmitted by using the power bias (ΔPp−m+2*ΔP1).

What is claimed is:
 1. An access method for the variable poweradjustment in the code division multiple access mobile communicationsystem, the said method is based on the base station and the userequipment, wherein, the acquisition information is obtained by the basestation through receiving on the up link the prefix of the physicalrandom access channel, the access prefix of the physical common packetchannel and the conflict detection prefix and evaluating the quality,respectively; the precise control of the transmission power of thesubsequent message section of the physical random access channel,conflict detection prefix of the physical common packet channel, and thepower control prefix, the message section are obtained based on thequality evaluation value; the control indication of the said precisecontrol is transmitted via the down link acquisition indication channel,access prefix acquisition indication channel, and conflictdetection/channel assignment indication channel; and after receiving thesaid power control indication by the user equipment, the subsequentmessage section of the physical random access channel, conflictdetection prefix of the physical common packet channel, and the powercontrol prefix, the message section are transmitted by using a valueamong a plurality of power bias values.
 2. An access method for thevariable power adjustment in the code division multiple access mobilecommunication system as claim 1, wherein, the format of the acquisitionindication channel and access prefix acquisition indication channelhaving the said precise control indication is:$a_{2k} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{1,s}{P_{s}(k)}}}$${a_{{2k} + 1} = {\sum\limits_{s = 0}^{15}\quad {{AI}_{2,s}{P_{s}(k)}}}},{k = 0},{{1{\cdots 15}};}$

wherein, Ps(k) is a prefix characteristic code, the values of AI₁ andAI₂ can be taken as 0, 1, and −1, nine control indications can beproduced by combining AI₁ and AI₂.
 3. An access method for the variablepower adjustment in the code division multiple access mobilecommunication system as claim 1, wherein, the format of the saidconflict detection/channel assignment indication channel is:$a_{2l} = {{\sum\limits_{i = 0}^{15}\quad {{CDI}_{i,1}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k,1}{P_{Sk}(l)}}}}$${a_{{2l} + 1} = {{\sum\limits_{i = 0}^{15}{{CDI}_{i,2}{P_{Si}(l)}}} + {\sum\limits_{k = 0}^{15}\quad {{CAI}_{k,2}{P_{Sk}(l)}}}}},{1 = 0},{{1{\cdots 15}};}$

wherein, CDI₁, CAI₂, can be taken as 0, 1, and −1; the definitions ofT₁, T₀, and T⁻¹ are as follows: T₁={(1, 1), (1, 0), (0, 1)}; T₀={(0, 0),(1, −1), (−1, 1)}; T⁻¹={(−1, −1), (−1, 0), (0, −1)}.
 4. An access methodfor the variable power adjustment in the code division multiple accessmobile communication system as claim 1, wherein, in the power adjustmentof the messages of the said physical random access channel, when theacquisition indications of the received down link acquisition indicationchannel are (0, 0), (1, −1), (−1, 1), then the prefixes will betransmitted by using continuously the power bias ΔP0; when (0, −1), (−1,0), (−1, −1) are received, then the access will be exited and reportedto the upper layer; when (1, 1) is received, then the messages will betransmitted by using the power bias ΔPp−m; when (1, 0) is received, thenthe messages will be transmitted by using the power bias ΔPp−m+ΔP1; when(0, 1) is received, then the messages will be transmitted by using thepower bias (ΔPp−m+2*ΔP1).
 5. An access method for the variable poweradjustment in the code division multiple access mobile communicationsystem as claim 1, wherein, after the down link access prefixacquisition indication channel is received by the said physical commonpacket channel, when the access prefix acquisition indications receivedby the user equipment on the down link are (0, 0), (1, −1), (−1, 1),then the access prefixes will be transmitted by using continuously thepower bias ΔP0; when (0, −1), (−1, 0), (−1, −1) are received, then theaccess will be exited and reported to the upper layer; when (1, 1) isreceived, then the messages will be transmitted by using the same powerbias; when (1, 0) is received, then the messages will be transmitted byusing the power bias ΔP1; when (0, 1) is received, then the messageswill be transmitted by using the power bias (2*ΔP1).
 6. An access methodfor the variable power adjustment in the code division multiple accessmobile communication system as claim 1, wherein, after the indicationsof the transmission power bias indicated by the conflictdetection/channel assignment indication channel are received by the saidphysical common packet channel, if it is in To set, then the accessprocedure will be exited; if those in T₁ or T⁻¹ set are received, thenan acquisition will be indicated, and the power biases of the subsequentpower control prefixes and the messages will be determined by thespecific values of T₁ or T⁻¹; when the received indication is (1, 1) or(−1, −1), then the power control prefixes and messages will betransmitted by using the power bias ΔPp−m; if the received indication is(1, 0) or (−1, 0), then the power control prefixes and messages will betransmitted by using the power bias (ΔPp−m+ΔP1); and if the receivedindication is (0, 1) or (0, −1), then the power control prefixes andmessages will be transmitted by using the power bias (ΔPp−m+2*ΔP1).